In my prior Australian patent 723519 and U.S. Pat. No. 6,074,553, I disclosed a solar-powered water skimmer of catamaran form that dragged a debris collection mesh bag to collect floating debris. A single electric motor turned a propeller to both move the skimmer forwards and assist in driving floating debris into the collection bag. This skimmer was fitted with forwardly facing probes that operated rudders to steer the device around or away from obstacles and/or the edges of the pool or lake. Though of value in swimming pools for leaf and blown-litter collection, this device did not cover the surface of the pool or pond in a very efficient manner, in part because it could not be reversed effectively because of the danger of entangling the propeller and bag.
U.S. Pat. No. 4,900,432 to Arnold et al also disclosed a solar-powered catamaran-style pool skimmer, which collected litter in a central compartment with the aid of a paddle wheel that was also used to propel the vessel forwards. While this skimmer was provided with a separate steering motor to turn the vessel when it contacted an object, it can readily get stuck in a pool corner because the paddle wheel and steering motors only turn in one direction. Indeed, reversal of the paddle wheel to back the vessel off from an object would probably result in the emptying of the litter collection chamber.
U.S. Pat. No. 5,106,492 to Distinti et al also disclosed a solar-powered catamaran-style pool-skimmer powered by a central paddle wheel that was used to move debris into a central collection compartment. This device also suffered from the danger that reversal of the paddle wheel would empty the collection compartment. Also, instead of having active means to steer the vessel after contact with an object, Distinti taught the use of a forwardly extending arm carrying a wheel (mounted for free rotation about a vertical axis) that served to guide or steer the vessel upon contact with a wall. This steering arrangement tends to make the vessel follow the wall until it gets to a corner, where it is likely to remain stuck. Distinti teaches the use of a sensor to detect when the collection compartment is full and to operate an alarm so that the owner can empty the compartment.